Such a joint connection-system with a device for axially prestressing the threaded, i.e. tap bolts is disclosed in the German Offenlegungsschrift 3,219,520. By axially prestressing such threaded or tap bolts, the danger of breaking them, which arises upon long-lasting dynamic loads, will be counteracted. In the kindred solution disclosed in the above Offenlegungsschrift, a so-called drive muff is used to rotate the tap bolt into a threaded borehole of a joint-adapter. This drive muff is irrotational because of a drive pin entering an axial groove in the shank of the tap bolt, but on the other hand it is axially displaceable along the said shank. The drive muff comprises a hexagonal segment to seat a wrench or the like and further a threaded segment onto which is screwed a prestressing muff with a corresponding threaded borehole. The prestressing muff projects axially beyond the threaded segment of the drive muff and also comprises a hexagonal segment at its outer periphery to seat a corresponding wrench or the like. Once the tap bolt has been screwed into the joint-adapter, it shall then be prestressed and the prestressing muff will be rotated relative to the drive muff. As a result the distance between a member-endpiece and joint-adapter is enlarged and the shank of the tap bolt is correspondingly prestressed. However this procedure is fairly cumbersome because of the need to use a drive muff and a prestressing muff for each member connection. Moreover it is fairly difficult to tightly control the magnitude of the prestressing force.